**1. Introduction**

Climate changes have been considered as a serious issue in the past few decades and have an impact on the agriculture production and human health. The climate variability and change are projected to result in the frequency of extremely high-temperature events, floods, and

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drought conditions. The global increase in temperature is predicted to enhance water losses due to high evapotranspiration rate and resulted in the increase of water stress. Many reports had been published that drought stress can impose decreasing of plants growth and losses in plant productivity. In addition, increasing human population that was predicted by US Census Bureau over 9 million in 2050, will need more demand for food, energy, and the residence. Expansion of city, as a consequence of increasing human occupancy, has significant impact on the displacement of farmland from well-irrigated system toward rain-fed marginal soil which might lose agriculture production.

occurrence under field condition is variable, influenced by variety and environmental conditions such as altitude and day length. Sugarcane is a cross-pollinating species although selfing occurs at low levels [3]. Sugarcane pollen is very small, rapidly desiccated, having a half-life only 12 minutes and no longer viable beyond 35 minutes and is immediately dried. Thus, biotechnological approach is believed to become crucial to overcome the limitations of classical sugarcane breeding. Development of transgenic sugarcane may foster the development for creation of new sugarcane cultivars with various important traits such as drought tolerance, high sucrose content, resistance to diseases, high yield of ethanol and biomass for fuels.

Biotechnology of Drought-Tolerant Sugarcane http://dx.doi.org/10.5772/intechopen.72436 141

Recently, it has been reviewed that understanding of water stress mechanism in sugarcane from molecular, biochemical, and physiological perspectives will be the most promising strategies for developing the biotechnology [1]. From the physiological perspective, to survive and develop normally, plants adapt to water stress with various strategies including altered gene expression [4] and accumulation of specific compound called compatible solutes such as proline, sugar alcohol, and betaine [5, 6]. Water stress increases the level of ABA, and the hormone involved in the signal transduction of gene expression converting the adaptation to the water stress [7, 8]. The change in water stress-related gene expression associated with sucrose accumulation and the genes encoding enzymes involved in amino acid metabolism have been reported in sugarcane [9, 10]. In addition, Glycine betaine (GB) is a compatible solute that is believed to act as an osmoprotectant and converting plant to adapt to the water stress condition in several plants including sugarcane. Understanding molecular and physiological mechanism on the water stress is a major challenge in developing biotechnology of drought-tolerant sugarcane. The objective of this review is to report the development of biotechnology of drought-tolerant sugarcane using the gene that induces glycine betaine accumulation as well as to summarize an efficient method for genetic transformation method mediated by *Agrobacterium* for sugarcane.

**2. Physiological and molecular drought stress responses in** 

normal growth, but if the stress was severe, some plants will not survive and dry.

Sugarcane is photosynthetically classified as C4 plant that adapted well in tropical climate. The C4 plants are often considered to be a better adapted to water limitation environments than most other crops, particularly as they are able to maintain leaf photosynthesis with slightly

Water stress is one of the most critical environmental abiotic stresses that affect plant's growth and productivity. It was estimated by the International Water Management Institute that by the year 2025, one third of the world will be occupied with severe water scarcity. Moreover, the climate change will induce competition between the use for human consumption and irrigation, which in turn affects the displacement of agriculture to non-irrigated marginal area that reduced in agricultural productivity. When subjected to water deficit or drought stress, plants undergo alteration in physiological started with reduction in protein synthesis, stomatal conductance and photosynthetic rate. Depending on the plants species, drought stress condition will accumulate the compatible solutes to protect cell from serious damage in drought stress tolerant plants. Under rehydration after mild water deficit, almost every plant can return to

**sugarcane**

Sugarcane is a major crop to produce sugar in tropical region and that sugar is extracted from sugarcane stem at sugarcane factory throughout the harvesting session. The stem is shredded, crushed, and pressed to produce juice that is separated from bagasse, the fibrous portion of sugarcane stem. The juice is then clarified and boiled to produce syrup, and through multiple rounds of crystallization to produce sucrose. The remaining black thick syrup called molasses is then separated as a by-product of sugarcane industry. Bagasse has several applications, including generation of power for the mill, papermaking, livestock feed and may be a useful source for production of various derivate of cellulose fiber, and fermentation of bagasse to produce ethanol. Due to still remaining high sugars, the molasses is used for alcohol and other fermentation products as well as a stock feed supplement. The molasses and another by-product called as filter cake are often used as a fertilizer on the cane fields. The various valuable products from sugarcane have put the plant as an economically important plant in tropical region. Increasing sugarcane production and processing would not only increase sugar supply and increase farmers income, but also enhance energy security by using bioethanol from sugarcane production and improve the environment.

Water is one of the most critical environments and plays a crucial role in the life of plants. The availability of water has a potential effect on plant's growth and productivity. The disruption of the plant water status due to drought stress condition reduces the plant survival, growth, and productivity in the environment. In the photosynthetically C4 plant species, sugarcane is considered a plant with high water-uptake efficiency. During day time, the C4 plants can slightly close their stomata to minimize evapotranspiration rate without any effect on photosynthetic carbon assimilation. Although sugarcane needs dry season before harvesting, the plant requires optimum water availability during the vegetative growth. Adequacy water supply during vegetative phase will enhance rapid growth, stem elongation, and internodes formation. On the other hand, limited water availability will stack sugarcane growth and seriously affect on sugar production [1]. Since sugarcane is a valuable crop in the tropical countries that is being used for sugar production and others products such as bioethanol, energy, feed, thus a strategy for development of new sugarcane cultivars tolerance to water stress will be an important issue.

The development of a new plant cultivar could be gained either by conventional breeding program or biotechnology approaches. Although sugarcane improvement by cross breeding program had been successfully implemented, creating a new variety through breeding program is laborious and take times around 12 years or even more. Sugarcane is a complex organism with high ploidy levels and chromosome number of 2n = 80 with a basic chromosome number (x) of 10 [2], and has limitation for the development of new cultivars. The flowering occurrence under field condition is variable, influenced by variety and environmental conditions such as altitude and day length. Sugarcane is a cross-pollinating species although selfing occurs at low levels [3]. Sugarcane pollen is very small, rapidly desiccated, having a half-life only 12 minutes and no longer viable beyond 35 minutes and is immediately dried. Thus, biotechnological approach is believed to become crucial to overcome the limitations of classical sugarcane breeding. Development of transgenic sugarcane may foster the development for creation of new sugarcane cultivars with various important traits such as drought tolerance, high sucrose content, resistance to diseases, high yield of ethanol and biomass for fuels.

drought conditions. The global increase in temperature is predicted to enhance water losses due to high evapotranspiration rate and resulted in the increase of water stress. Many reports had been published that drought stress can impose decreasing of plants growth and losses in plant productivity. In addition, increasing human population that was predicted by US Census Bureau over 9 million in 2050, will need more demand for food, energy, and the residence. Expansion of city, as a consequence of increasing human occupancy, has significant impact on the displacement of farmland from well-irrigated system toward rain-fed marginal

Sugarcane is a major crop to produce sugar in tropical region and that sugar is extracted from sugarcane stem at sugarcane factory throughout the harvesting session. The stem is shredded, crushed, and pressed to produce juice that is separated from bagasse, the fibrous portion of sugarcane stem. The juice is then clarified and boiled to produce syrup, and through multiple rounds of crystallization to produce sucrose. The remaining black thick syrup called molasses is then separated as a by-product of sugarcane industry. Bagasse has several applications, including generation of power for the mill, papermaking, livestock feed and may be a useful source for production of various derivate of cellulose fiber, and fermentation of bagasse to produce ethanol. Due to still remaining high sugars, the molasses is used for alcohol and other fermentation products as well as a stock feed supplement. The molasses and another by-product called as filter cake are often used as a fertilizer on the cane fields. The various valuable products from sugarcane have put the plant as an economically important plant in tropical region. Increasing sugarcane production and processing would not only increase sugar supply and increase farmers income, but also enhance energy security by using bio-

Water is one of the most critical environments and plays a crucial role in the life of plants. The availability of water has a potential effect on plant's growth and productivity. The disruption of the plant water status due to drought stress condition reduces the plant survival, growth, and productivity in the environment. In the photosynthetically C4 plant species, sugarcane is considered a plant with high water-uptake efficiency. During day time, the C4 plants can slightly close their stomata to minimize evapotranspiration rate without any effect on photosynthetic carbon assimilation. Although sugarcane needs dry season before harvesting, the plant requires optimum water availability during the vegetative growth. Adequacy water supply during vegetative phase will enhance rapid growth, stem elongation, and internodes formation. On the other hand, limited water availability will stack sugarcane growth and seriously affect on sugar production [1]. Since sugarcane is a valuable crop in the tropical countries that is being used for sugar production and others products such as bioethanol, energy, feed, thus a strategy for development of new sugarcane cultivars tolerance to water stress will

The development of a new plant cultivar could be gained either by conventional breeding program or biotechnology approaches. Although sugarcane improvement by cross breeding program had been successfully implemented, creating a new variety through breeding program is laborious and take times around 12 years or even more. Sugarcane is a complex organism with high ploidy levels and chromosome number of 2n = 80 with a basic chromosome number (x) of 10 [2], and has limitation for the development of new cultivars. The flowering

soil which might lose agriculture production.

140 Sugarcane - Technology and Research

be an important issue.

ethanol from sugarcane production and improve the environment.

Recently, it has been reviewed that understanding of water stress mechanism in sugarcane from molecular, biochemical, and physiological perspectives will be the most promising strategies for developing the biotechnology [1]. From the physiological perspective, to survive and develop normally, plants adapt to water stress with various strategies including altered gene expression [4] and accumulation of specific compound called compatible solutes such as proline, sugar alcohol, and betaine [5, 6]. Water stress increases the level of ABA, and the hormone involved in the signal transduction of gene expression converting the adaptation to the water stress [7, 8]. The change in water stress-related gene expression associated with sucrose accumulation and the genes encoding enzymes involved in amino acid metabolism have been reported in sugarcane [9, 10]. In addition, Glycine betaine (GB) is a compatible solute that is believed to act as an osmoprotectant and converting plant to adapt to the water stress condition in several plants including sugarcane. Understanding molecular and physiological mechanism on the water stress is a major challenge in developing biotechnology of drought-tolerant sugarcane. The objective of this review is to report the development of biotechnology of drought-tolerant sugarcane using the gene that induces glycine betaine accumulation as well as to summarize an efficient method for genetic transformation method mediated by *Agrobacterium* for sugarcane.
